Subject: Re: Is autovacuum doing a wraparound-avoiding VACUUM?
From: Simon Riggs <simon@2ndquadrant.com>
To: Alvaro Herrera <alvherre@commandprompt.com>
Cc: List pgsql-patches <pgsql-patches@postgresql.org>
In-Reply-To: <20080717211044.GR3934@alvh.no-ip.org>
References: <1216227339.19656.364.camel@ebony.2ndQuadrant>
	<20080717211044.GR3934@alvh.no-ip.org>
Content-Type: text/plain
Date: Fri, 18 Jul 2008 00:02:09 +0100
Message-Id: <1216335729.19656.683.camel@ebony.2ndQuadrant>
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On Thu, 2008-07-17 at 17:10 -0400, Alvaro Herrera wrote:
> Simon Riggs wrote:
> > 
> > Is autovacuum doing a wraparound-avoiding VACUUM?
> > Currently, no easy way to tell.
> > 
> > Patch to change message of autovac in pg_stat_activity when we are
> > performing an anti-wraparound VACUUM.
> 
> I just obsoleted this patch.  The new patch should be easier to do
> though -- just a one line change I think.
> 
> I don't like your wording though; it feels too verbose (and you're
> losing the ANALYZE in case it's doing both things).  How about 
> 
> 	snprintf(activity, MAX_AUTOVAC_ACTIV_LEN,
> 		"autovacuum: VACUUM%s%s", vac
> 		tab->at_doanalyze ? " ANALYZE" : "",
> 		tab->at_wraparound ? " (wraparound)" : "");

Yes, looks good.

Losing the ANALYZE was conscious, but in retrospect is something we
might live to regret. Yours is better.

> You're not proposing it for 8.3 right?

I think I am. It's an important diagnostic for your other fix.

We need to be able to tell the difference between a wraparound and other
weird situations.

-- 
 Simon Riggs           www.2ndQuadrant.com
 PostgreSQL Training, Services and Support